They love to get in a jam Wednesdays

What would happen if a few jazz musicians gathered in a living room late at night and proceeded to riff?

Probably something like the scene that unfolds every Wednesday evening at the Viaduct Theater on North Western Avenue.

Less a formal show than a laid-back jam session, the Wednesday night get-together practically obliterates any distance between performers and listeners. Both gathered near the bar at the Viaduct on a recent Wednesday, the musicians schmoozing with the crowd between every number.

FOR THE RECORD - This story contains corrected material, published May 9, 2008.

Often, the audience of regulars requested obscure tunes. Occasionally, the band members obliged. Either way, the easy give-and-take among the participants represented something different in Chicago jazz.

Certainly, the nonchalance of the setting had an obvious effect on the proceedings. In any other context, a band that includes organist Dan Trudell and saxophonist Pat Mallinger could be counted on to make a certain amount of noise.

Trudell stands among the best organists in the city, his nimble technique matched by a tautly coiled approach to rhythm and tempo. Mallinger, meanwhile, is a reedist for all occasions but can address the hard-bop vocabulary with ample aggression.

Yet in this setting, Trudell and Mallinger -- as well as keyboardist Brian OHern (the name as published has been corrected here and in subsequent references in this text) and drummer Gerald Dowd -- took it relatively easy. Slipping from a lovely tune by Antonio Carlos Jobim to a novelty song by OHern to an atmospheric piece by Trudell, the emphasis was on an easy, late-night flow. Granted, some of this music sounded a bit diffuse. With Trudell offering chordal fills on organ and synthesized effects on laptop, and with various players doubling on keyboards, the ensemble often conveyed a jam-band sensibility.

A little of that goes a long way, which is why at least one listener was relieved to encounter the nervous energy of Mallinger's "Worried" and the romantic ardor of "Laura."

But Wednesday nights now have something new to recommend them.

Note: Paul Wertico has been named head of jazz studies and assistant professor at Chicago College of Performing Arts at Roosevelt University.

Dan Trudell and friends play at 9 p.m. Wednesdays at the Viaduct Theater, 3111 N. Western Ave.; $5; 773-296-6024.